Upload
others
View
4
Download
0
Embed Size (px)
Citation preview
Tsunami Hazard
Tsu = harbor
Nami = wave
(Japanese terms)
A tsunami is a series of travelling
waves most commonly generated
by vertical displacements of the sea
floor associated with earthquakes
below or near the ocean floor that
cause a huge amount of seawater
to be abruptly displaced.
What is a Tsunami?
Near-field/ local Tsunamis Near-field tsunamis: tsunamis that occur within 200 km of the epicentre of an earthquake
Local tsunamis: tsunami from a nearby source for which its destructive effects are confined to coasts within less than 200 km
Far-field Tsunamis Far-field tsunamis: a tsunami originating from thousands of kilometres from the affected areas; usually starting as a near-field tsunami that causes extensive destruction near the source and additional casualties and destruction on shores more than 1000 km from its source
Categories of Tsunamis
1. Vertical movement of the seafloor related to
subduction zone earthquakes (95)
2. Submarine volcanic eruptions (5)
3. Submarine landslides (1)
4. Extraterrestrial: Meteor impact
(Approx. number of tsunamis for different sources since 1900 in Indonesia)
What Cause a Tsunami?
The Tectonic Plate Movement
6 Earthquake
Principles of Plate Tectonics
Subduction Zone
Vertical Movement generates Tsunami
Located under the sea (submarine
earthquake)
Depth of the centre of the submarine
earthquake is less than 100 km
Magnitude 7 or more in Richter Scale
The movement of the tectonic plate occurs
vertically
Parameter for Tsunamigenic Earthquakes
Tsunami Prone Areas in Indonesia
Destructive Earthquakes and Tsunamis in Indonesia (1992 – April 2012)
EARTHQUAKE AND TSUNAMI
EARTHQUAKE
Lampung 1994
Jambi 1995
Alor 2004
Timor 1995 NTT 1992
Biak 1996
Banyuwangi 1994 Pangandaran 2006
Irian Jaya 2002
Aceh 2004 Minahasa Peninsula 1996
Sumbar 2005
Nias 2005
Seram 2006
Bengkulu 2007
Padang 2009
Tasikmalaya 2009
Papua 2009
Mentawai 2010
Maluku 1994
Sulteng 1997
Maluku 1998 Banggai 2000
Bengkulu 2000
Aceh 2002
NTT 2003
Sulut 2003
NTB 2004
Irian Jaya 2004
NTT 2004
Sumbar 2007
NTB 2007
Minahasa 2008
Papua Serui 2010
Papua 2011
Aceh 2012
Jateng 2006
Tsunami Characteristics
Ground shaking from a strong earthquake
Seawater withdrawal in a very quick and
unusual way
A roaring sound that resembles the sound of an
airplane of train
Strong winds blow from the sea to the coast
Unusually smells waft from the beach
Unusual animal behavior: p.e. animals run
away from the coast
Natural Warning Signs
The Impact of Tsunamis
Damages caused by Tsunamis
Tsunami Hazard Assessment
• Information on source areas
• Historical events
• Paleo-tsunami studies
• Scenarios
• Estimated travel times from source areas
• Wave height at coast
• Areas inland to be affected by tsunamis (in terms
of maximum inundation, flow depths, probability)
Approaches for Hazard Mapping
1. “Bathtube” Model - based on topography only:
Kuta / Lombok
2. Based on topography but incorporating local
knowledge and a rule based wave attenuation
factor: Bantul
3. Single scenario approach - most credible or worst
case: Padang
4. Multi-scenario approaches: Southern Bali
Level 1: Tsunami Hazard Map for Kuta-Lombok
Level 2: Tsunami Hazard Map for Bantul
Level 3: Tsunami Inundation Map for Padang
Level 4: Tsunami Hazard Map for southern Bali
Hazard & Disaster Risk
Natural hazards do not necessarily cause disasters. A disaster occurs only
if a population is exposed to the natural hazard and cannot cope with its
effects.
Hazard: A dangerous phenomenon, substance,
human activity or condition that may cause loss of life,
injury or other health impacts, property damage, loss
of livelihoods and services, social and economic
disruption, or environmental damage
Vulnerability: The characteristics and circumstances
of a community, system or asset that make it
susceptible to the damaging effects of a hazard
Risk: The combination of the probability of an event
and its negative consequences
UNISDR Terminology
www.gitews.org/tsunami-kit
Project for Training, Education and Consulting for
Tsunami Early Warning System (PROTECTS)
Capacity Development in Local Communities